Converter device

Abstract

The purpose of the present invention is to achieve high efficiency and high efficiency. In the present invention, a converter device (1) comprises a rectifier (2), a half bridge inverter (3), an input inductor (Lin), a transformer (Tr1), a full bridge inverter (4), an inductor (L1), and a control device (5). The transformer (Tr1) has a primary winding (N1) connected between a first output end (34) and a second output end (35) in the half bridge inverter (3). The full bridge inverter (4) is connected to a secondary winding (N2) of the transformer (Tr1). The inductor (L1) is connected between the half bridge inverter (3) and the primary winding (N1) or between the secondary winding (N2) and the full bridge inverter (4). The control device (5) controls the half bridge inverter (3) and the full bridge inverter (4).

Description

Technical Field

[0001] The present disclosure relates to a converter device, and more particularly to a converter device including a transformer.

Background Art

[0002] Patent Document 1 discloses a power conversion device (converter device) that converts input power from an AC power source into desired DC power. The power conversion device disclosed in Patent Document 1 includes a transformer.

[0003] In a converter device including a transformer, further improvement in power factor and efficiency may be desired.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

[0005] An object of the present disclosure is to provide a converter device capable of achieving higher power factor and higher efficiency.

[0006] A converter device according to one aspect of the present disclosure comprises a rectifier, a half-bridge inverter, an input inductor, a transformer, a full-bridge inverter, an inductor, and a control device. The rectifier is composed of a first diode and a second diode connected in series with the first diode. In the rectifier, the first AC output terminal of the AC power supply is connected to the connection point between the first diode and the second diode. The half-bridge inverter has a first series circuit of a first semiconductor switching element and a second semiconductor switching element, and a second series circuit of a first capacitor and a second capacitor. The second series circuit is connected in parallel with the first series circuit. In the half-bridge inverter, the first semiconductor switching element is connected to the cathode of the first diode, and the second semiconductor switching element is connected to the anode of the second diode. In the half-bridge inverter, the second AC output terminal of the AC power supply is connected to the connection point between the first semiconductor switching element and the second semiconductor switching element. The input inductor is connected between the AC power supply and the rectifier or the half-bridge inverter. The transformer includes a primary winding and a secondary winding. The primary winding of the transformer is connected between the first output terminal of the half-bridge inverter between the first semiconductor switching element and the second semiconductor switching element, and between the second output terminal of the half-bridge inverter between the first capacitor and the second capacitor. The full-bridge inverter is connected to the secondary winding of the transformer. The full-bridge inverter has a third semiconductor switching element, a fourth semiconductor switching element, a fifth semiconductor switching element, and a sixth semiconductor switching element. The inductor is connected between the first output terminal of the half-bridge inverter and the primary winding, or between the second output terminal of the half-bridge inverter and the primary winding, or between the secondary winding and the full-bridge inverter. The control device controls the half-bridge inverter and the full-bridge inverter. The control device controls the DC bus voltage of the half-bridge inverter and controls the output voltage of the full-bridge inverter.

[0007] A converter device according to another aspect of the present disclosure comprises a rectifier, a first half-bridge inverter, an input inductor, a transformer, an inductor, a second half-bridge inverter, and a control device. The rectifier is composed of a first diode and a second diode connected in series with the first diode. In the rectifier, the first AC output terminal of an AC power supply is connected to the connection point between the first diode and the second diode. The first half-bridge inverter has a first series circuit of a first semiconductor switching element and a second semiconductor switching element, and a second series circuit of a first capacitor and a second capacitor. The second series circuit is connected in parallel with the first series circuit. In the first half-bridge inverter, the first semiconductor switching element is connected to the cathode of the first diode, and the second semiconductor switching element is connected to the anode of the second diode. In the first half-bridge inverter, the second AC output terminal of the AC power supply is connected to the connection point between the first semiconductor switching element and the second semiconductor switching element. The input inductor is connected between the AC power supply and the rectifier or the first half-bridge inverter. The transformer includes a primary winding and a secondary winding. The primary winding of the transformer is connected between the first output terminal of the first half-bridge inverter between the first semiconductor switching element and the second semiconductor switching element, and between the second output terminal of the half-bridge inverter between the first capacitor and the second capacitor. The inductor is connected between the first or second output terminal of the first half-bridge inverter and the primary winding. The second half-bridge inverter is connected to the secondary winding of the transformer. The second half-bridge inverter has a third semiconductor switching element, a fourth semiconductor switching element, a third capacitor, and a fourth capacitor. The control device controls the first half-bridge inverter and the second half-bridge inverter. The control device controls the DC bus voltage of the first half-bridge inverter and controls the output voltage of the second half-bridge inverter. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a circuit diagram of a converter device according to Embodiment 1. [Figure 2] Figure 2 is a timing chart illustrating the operation of the converter device described above. [Figure 3] Figure 3 is an explanatory diagram of the operation of the converter device described above when the polarity of the input voltage is positive. [Figure 4] Figures 4A to 4C illustrate the operation of the converter device described above when the input voltage polarity is positive. [Figure 5] Figure 5 shows the operating waveform of the converter device described above. [Figure 6] Figure 6 is an explanatory diagram of the operation of the converter device described above when the polarity of the input voltage is negative. [Figure 7] Figures 7A to 7C illustrate the operation of the converter device described above when the input voltage polarity is negative. [Figure 8] Figure 8 is a graph showing the relationship between the DC bus voltage and output power when the switching frequency is changed for the converter device described above. [Figure 9] Figure 9 shows the operating waveform of the converter device described above. [Figure 10] Figure 10A is a magnified view of the operating waveform of the converter device described above when the output power is 100W. Figure 10B is a magnified view of the operating waveform of the converter device described above when the output power is 50W. [Figure 11] Figure 11 is a circuit diagram of the converter device according to Embodiment 2. [Figure 12] Figure 12 is a circuit diagram of a converter device according to a modified example of Embodiment 1. [Modes for carrying out the invention]

[0009] (Embodiment 1) In the following, the converter device 1 according to Embodiment 1 will be described with reference to Figures 1 to 10B.

[0010] (1) Overview The converter device 1 according to Embodiment 1 is an isolated AC-DC converter equipped with a transformer Tr1, as shown in Figure 1. The converter device 1 includes a rectifier 2, a half-bridge inverter 3, an input inductor Lin, a transformer Tr1, an inductor L1, a full-bridge inverter 4, and a control device 5. The converter device 1 also further includes an input filter 6.

[0011] Furthermore, the converter device 1 is equipped with a plurality of external connection terminals. The plurality of external connection terminals include a first input terminal 11, a second input terminal 12, a first output terminal 13, and a second output terminal 14. An AC power supply 8 is connected between the first input terminal 11 and the second input terminal 12 of the converter device 1. In the converter device 1, the input voltage Vin input from the AC power supply 8 is, for example, a sinusoidal AC voltage. The AC power supply 8 includes, for example, a commercial power supply.

[0012] A load is connected between the first output terminal 13 and the second output terminal 14 of the converter device 1, for example, via a DC-DC converter that converts the output voltage of the converter device 1. The load includes, for example, mobile devices such as smartphones, notebook personal computers, or LED (Light Emitting Diode) lighting equipment. Alternatively, the load may be directly connected between the first output terminal 13 and the second output terminal 14 of the converter device 1 without the need for other circuits such as a DC-DC converter.

[0013] (2) Details The converter device 1 according to Embodiment 1 will be described in more detail below with reference to Figures 1 to 9.

[0014] (2.1) External connection terminals As described above, the multiple external connection terminals include a first input terminal 11, a second input terminal 12, a first output terminal 13, and a second output terminal 14.

[0015] An AC power supply 8 is connected between the first input terminal 11 and the second input terminal 12. More specifically, the first AC output terminal 81 of the AC power supply 8, which has a first AC output terminal 81 and a second AC output terminal 82, is connected to the first input terminal 11. The second AC output terminal 82 of the AC power supply 8 is connected to the second input terminal 12.

[0016] (2.2) Rectifier Rectifier 2 consists of a first diode D1 and a second diode D2 connected in series with the first diode D1. In rectifier 2, the first AC output terminal 81 of the AC power supply 8 is connected to the connection point 21 between the first diode D1 and the second diode D2. More specifically, the connection point 21 of rectifier 2 is connected to the first AC output terminal 81 of the AC power supply 8 via the inductor Lf and input inductor Lin of the input filter 6.

[0017] (2.3) Input Filter The input filter 6 is a low-pass filter composed of, for example, an L-type LC filter including an inductor Lf and a capacitor Cf. The cutoff frequency of the low-pass filter is higher than the frequency of the AC power supply 8 and lower than the switching frequencies of the first semiconductor switching element Q1 and the second semiconductor switching element Q2.

[0018] (2.4) Input Inductor The input inductor Lin is connected between the first AC output terminal 81 of the AC power supply 8 and the connection point 21 of the rectifier 2. The input inductor Lin has a first terminal and a second terminal. The first terminal of the input inductor Lin is connected to the inductor Lf of the input filter 6, and via the inductor Lf, it is connected to the first AC output terminal 81 of the AC power supply 8. The second terminal of the input inductor Lin is connected to the connection point 21 of the first diode D1 and the second diode D2 in the rectifier 2. In other words, the second terminal of the input inductor Lin is connected to the anode of the first diode D1 and the cathode of the second diode D2.

[0019] (2.5) Half-bridge inverter The half-bridge inverter 3 includes a first series circuit 31 of a first semiconductor switching element Q1 and a second semiconductor switching element Q2, and a second series circuit 32 of a first capacitor C1 and a second capacitor C2. The second series circuit 32 is connected in parallel to the first series circuit 31. In the half-bridge inverter 3, the first semiconductor switching element Q1 is connected to the cathode of the first diode D1, and the second semiconductor switching element Q2 is connected to the anode of the second diode D2. In the half-bridge inverter 3, the second AC output terminal 82 of the AC power supply 8 is connected to the connection point 33 between the first semiconductor switching element Q1 and the second semiconductor switching element Q2.

[0020] In the half-bridge inverter 3, each of the first semiconductor switching element Q1 and the second semiconductor switching element Q2 has a control terminal, a first main terminal, and a second main terminal. The control terminals of the first semiconductor switching element Q1 and the second semiconductor switching element Q2 are connected to the control device 5. The first semiconductor switching element Q1 is turned on and off in response to a first switching signal S1 provided by the control device 5. The second semiconductor switching element Q2 is turned on and off in response to a second switching signal S2 provided by the control device 5. The first semiconductor switching element Q1 and the second semiconductor switching element Q2 are, for example, GaN-based GITs (Gate Injection Transistors). In the first semiconductor switching element Q1 and the second semiconductor switching element Q2, the control terminal, the first main terminal, and the second main terminal are the gate terminal, drain terminal, and source terminal, respectively. Each of the first semiconductor switching element Q1 and the second semiconductor switching element Q2 has parasitic capacitance between the first main terminal (drain terminal) and the second main terminal (source terminal).

[0021] In the half-bridge inverter 3, the drain terminal of the first semiconductor switching element Q1 is connected to the cathode of the first diode D1, the source terminal of the first semiconductor switching element Q1 is connected to the drain terminal of the second semiconductor switching element Q2, and the source terminal of the second semiconductor switching element Q2 is connected to the anode of the second diode D2.

[0022] In the half-bridge inverter 3, the first terminal of the first capacitor C1 is connected to the drain terminal of the first semiconductor switching element Q1 and the cathode of the first diode D1, the second terminal of the first capacitor C1 is connected to the first terminal of the second capacitor C2, and the second terminal of the second capacitor C2 is connected to the source terminal of the second semiconductor switching element Q2 and the anode of the second diode D2.

[0023] (2.6) Transformers Transformer Tr1 includes a primary winding N1 and a secondary winding N2. The primary winding N1 of transformer Tr1 is connected between the first output terminal 34 between the first semiconductor switching element Q1 and the second semiconductor switching element Q2 in the half-bridge inverter 3, and between the second output terminal 35 between the first capacitor and the second capacitor in the half-bridge inverter 3.

[0024] In transformer Tr1, the number of turns in the primary winding N1 is greater than the number of turns in the secondary winding N2.

[0025] (2.7) Inductors Inductor L1 is connected between the first output terminal 34 of the half-bridge inverter 3 and the primary winding N1. Inductor L1 is not limited to being connected between the first output terminal 34 of the half-bridge inverter 3 and the primary winding N1; for example, it may be connected between the second output terminal 35 of the half-bridge inverter 3 and the primary winding N1. Inductor L1 is a separate inductor (electronic component) from transformer Tr1, but is not limited to this; it may also be a leakage inductance connected to the primary winding in the equivalent circuit of the transformer.

[0026] (2.8) Full-bridge inverter The full-bridge inverter 4 is connected to the secondary winding N2 of the transformer Tr1. The full-bridge inverter 4 has a third semiconductor switching element Q3, a fourth semiconductor switching element Q4, a fifth semiconductor switching element Q5, and a sixth semiconductor switching element Q6.

[0027] More specifically, the full-bridge inverter 4 includes a series circuit 41 of a third semiconductor switching element Q3 and a fourth semiconductor switching element Q4, a series circuit 42 of a fifth semiconductor switching element Q5 and a sixth semiconductor switching element Q6, and an output capacitor Co. The series circuit 41 of the third semiconductor switching element Q3 and the fourth semiconductor switching element Q4 is connected between the first output terminal 13 and the second output terminal 14. The series circuit 42 of the fifth semiconductor switching element Q5 and the sixth semiconductor switching element Q6 is connected between the first output terminal 13 and the second output terminal 14. The output capacitor Co is connected between the first output terminal 13 and the second output terminal 14.

[0028] Furthermore, the full-bridge inverter 4 has a third diode D3, a fourth diode D4, a fifth diode D5, and a sixth diode D6. The third diode D3 is connected in reverse parallel to the third semiconductor switching element Q3. The fourth diode D4 is connected in reverse parallel to the fourth semiconductor switching element Q4. The fifth diode D5 is connected in reverse parallel to the fifth semiconductor switching element Q5. The sixth diode D6 is connected in reverse parallel to the sixth semiconductor switching element Q6.

[0029] In the full-bridge inverter 4, each of the third to sixth semiconductor switching elements Q3 to Q6 has a control terminal, a first main terminal, and a second main terminal. The control terminals of the third to sixth semiconductor switching elements Q3 to Q6 are connected to the control device 5. The third to sixth semiconductor switching elements Q3 to Q6 are turned on and off in response to the third to sixth switching signals S3 to S6 provided by the control device 5. The third to sixth semiconductor switching elements Q3 to Q6 are, for example, MOSFETs (Metal-Oxide-Semiconductor Field Effect Transistors). More specifically, each of the third to sixth semiconductor switching elements Q3 to Q6 is an n-channel MOSFET. Here, the n-channel MOSFET is a normally-off type Si-based MOSFET. In the third to sixth semiconductor switching elements Q3 to Q6, the control terminal, the first main terminal, and the second main terminal are the gate terminal, drain terminal, and source terminal, respectively.

[0030] In the full-bridge inverter 4, the drain terminal of the third semiconductor switching element Q3 is connected to the first output terminal 13, the source terminal of the third semiconductor switching element Q3 is connected to the drain terminal of the fourth semiconductor switching element Q4, and the source terminal of the fourth semiconductor switching element Q4 is connected to the second output terminal 14.

[0031] In addition, in the full-bridge inverter 4, the drain terminal of the fifth semiconductor switching element Q5 is connected to the first output terminal 13, the source terminal of the fifth semiconductor switching element Q5 is connected to the drain terminal of the sixth semiconductor switching element Q6, and the source terminal of the sixth semiconductor switching element Q6 is connected to the second output terminal 14.

[0032] In the full-bridge inverter 4, the third to sixth diodes D3 to D6 are parasitic diodes of the MOSFETs of the third to sixth semiconductor switching elements Q3 to Q6, respectively. Each of the third to sixth diodes D3 to D6 has an anode and a cathode. The anode and cathode of each of the third to sixth diodes D3 to D6 are connected to the second main terminal (source terminal) and the first main terminal (drain terminal) of the corresponding semiconductor switching element among the third to sixth semiconductor switching elements Q3 to Q6, respectively. Each of the third to sixth semiconductor switching elements Q3 to Q6 has a parasitic capacitance between the first main terminal (drain terminal) and the second main terminal (source terminal).

[0033] The full-bridge inverter 4 has a first input terminal 44 between the third semiconductor switching element Q3 and the fourth semiconductor switching element Q4, and a second input terminal 45 between the fifth semiconductor switching element Q5 and the sixth semiconductor switching element Q6. In the full-bridge inverter 4, the secondary winding N2 of the transformer Tr1 is connected between the first input terminal 44 and the second input terminal 45.

[0034] (2.9) Control device The control device 5 controls the half-bridge inverter 3 and the full-bridge inverter 4. The control device 5 controls the first semiconductor switching element Q1 and the second semiconductor switching element Q2 of the half-bridge inverter 3. The control device 5 also controls the third semiconductor switching element Q3, the fourth semiconductor switching element Q4, the fifth semiconductor switching element Q5, and the sixth semiconductor switching element Q6 of the full-bridge inverter 4. The control device 5 is configured to provide the first to sixth switching signals (control signals) S1 to S6 to each of the first to sixth semiconductor switching elements Q1 to Q6. The first to sixth switching signals S1 to S6 are gate voltages (gate signals) applied between the control terminals of the first to sixth semiconductor switching elements Q1 to Q6 and the second main terminal in order to turn the first to sixth semiconductor switching elements Q1 to Q6 on and off. The first to sixth switching signals S1 to S6 are voltages whose voltage level changes between a voltage level higher than the threshold voltage (gate threshold voltage) of the first to sixth semiconductor switching elements Q1 to Q6 (hereinafter also referred to as high level) and a voltage level lower than the threshold voltage (hereinafter also referred to as low level). The control device 5 is configured to change the frequency of the first to sixth switching signals S1 to S6.

[0035] The control device 5, for example as shown in Figure 2, sets the duty cycle of the first switching signal S1 that controls the first semiconductor switching element Q1 to 50%, and the duty cycle of the second switching signal S2 that controls the second semiconductor switching element Q2 to 50%. The duty cycle of the first switching signal S1 is the ratio of the high-level period to the total time of the high-level period and low-level period in one cycle of the first switching signal S1. The duty cycle of the second switching signal S2 is the ratio of the high-level period to the total time of the high-level period and low-level period in one cycle of the second switching signal S2.

[0036] For example, when the polarity of the input voltage Vin from the AC power supply 8 is positive (the direction in which the first AC output terminal 81 is at a higher potential than the second AC output terminal 82, as shown by the arrow in Figure 1), the control device 5 outputs a first switching signal S1 and a second switching signal S2 that are generated so as shown in Figure 3, that a first on period (first period T1 in Figure 3), a dead time period Td, a second on period (the combined period of the second period T2 and the third period T3 in Figure 3), and a dead time period Td are repeated. The first on period is the period in which the first switching signal S1 is set to a high level and the second switching signal S2 is set to a low level. The first period T1 is the charging period of the input inductor Lin. The dead time period Td is the period in which both the first switching signal S1 and the second switching signal S2 are set to a low level. The second ON period is the period in which the first switching signal S1 is set to a low level and the second switching signal S2 is set to a high level. The second period T2 is the discharge period of the input inductor Lin. The third period T3 is the zero-current period in which no current flows through the input inductor Lin.

[0037] Furthermore, the control device 5 sets the duty cycle of the third switching signal S3 that controls the third semiconductor switching element Q3 to 50%, as shown in Figure 2, for example. The control device 5 also sets the duty cycle of the fourth switching signal S4 that controls the fourth semiconductor switching element Q4 to 50%, the fifth switching signal S5 that controls the fifth semiconductor switching element Q5 to 50%, and the sixth switching signal S6 that controls the sixth semiconductor switching element Q6 to 50%. The duty cycle of each of the third to sixth switching signals S3 to S6 is the ratio of the high-level period to the total time of the high-level period and low-level period in one cycle of the third to sixth switching signals S3 to S6.

[0038] Figure 2 shows the relationship between the first to sixth switching signals S1 to S6, the output voltage V1 of the half-bridge inverter 3, and the input voltage V2 of the full-bridge inverter 4. The output voltage V1 of the half-bridge inverter 3 is the voltage between the first output terminal 34 and the second output terminal 35, with the potential of the second output terminal 35 as the reference potential. The input voltage V2 of the full-bridge inverter 4 is the voltage between the first input terminal 44 and the second input terminal 45, with the potential of the second input terminal 45 as the reference potential.

[0039] Figure 3 shows the first switching signal S1 and the second switching signal S2, and the current i flowing through the input inductor Lin, when the polarity of the input voltage Vin from the AC power supply 8 is positive (as shown by the direction of the arrow in Figure 1, the first AC output terminal 81 is at a higher potential than the second AC output terminal 82). L The relationship between the output voltage V1 of the half-bridge inverter 3 and the given signal is illustrated in the diagram.

[0040] Figures 4A, 4B, and 4C are explanatory diagrams of the operation of the first period T1, second period T2, and third period T3, respectively, in Figure 3. In Figures 4A and 4B, the current i flowing through the input inductor Lin is shown. L The current path (see Figure 5) is shown by a thin dashed line. During the first period T1, energy is stored in the input inductor Lin. During the second period T2, the energy is released from the input inductor Lin. The third period T3 is the period during which the current flowing through the input inductor Lin becomes zero, so in Figure 4C, the current i flowing through the input inductor Lin is shown. L This is not shown in the diagram. Also, in Figures 4A, 4B, and 4C, the current i1 flowing through the primary winding N1 of transformer Tr1 (the current i1 flowing through inductor L1) is shown by a thick dashed line.

[0041] In the first period T1 in Figure 3, the first semiconductor switching element Q1 is ON and the second semiconductor switching element Q2 is OFF. Therefore, as shown in Figure 4A, current i flows to the input inductor Lin through the path of input inductor Lin - first diode D1 - first semiconductor switching element Q1 - connection point 33. LA current flows. In the first period T1 shown in Figure 3, the current i flowing through the input inductor Lin increases with time elapsed from the start of the first period T1, as shown in Figure 3. L As the current increases, energy is stored in the input inductor Lin. Also, during the first period T1 in Figure 3, as shown in Figure 4A, current i1 flows through the path of first capacitor C1 - first semiconductor switching element Q1 - inductor L1 - primary winding N1 - first capacitor C1.

[0042] At the end of the first period T1 and after the dead time period Td has elapsed, the voltage across the second semiconductor switching element Q2 has dropped to zero volts. As a result, the second semiconductor switching element Q2 is switched to zero volts at the start of the second period T2.

[0043] In the second period T2 of Figure 3, the first semiconductor switching element Q1 is off and the second semiconductor switching element Q2 is on. Therefore, as shown in Figure 4B, current i flows through the path of input inductor Lin - first diode D1 - first capacitor C1 - second capacitor C2 - second semiconductor switching element Q2 - connection point 33. L A current flows. At this time, the stored energy of the input inductor Lin is released from the input inductor Lin, and the current i increases with the passage of time from the start of the second period T2. L It decreases to zero. Also, in the second period T2 in Figure 3, current i1 flows through the path of second capacitor C2 - primary winding N1 - inductor L1 - first output terminal 34 - second semiconductor switching element Q2 - second capacitor C2.

[0044] In the third period T3 of Figure 3, current i1 flows through the path from the second capacitor C2 - primary winding N1 - inductor L1 - first output terminal 34 - second semiconductor switching element Q2 - second capacitor C2.

[0045] Figure 6 shows the first switching signal S1 and the second switching signal S2, and the current i flowing through the input inductor Lin, when the polarity of the input voltage Vin from the AC power supply 8 is negative. L The relationship between the output voltage V1 of the half-bridge inverter 3 and the given signal is illustrated in the diagram.

[0046] When the polarity of the input voltage Vin from the AC power supply 8 is negative, as shown in FIG. 6, the control device 5 generates the first switching signal S1 and the second switching signal S2 such that the third on-period (the fourth period T11 in FIG. 6), the dead time period Td, the fourth on-period (the period obtained by combining the fifth period T12 and the sixth period T13 in FIG. 3), and the dead time period Td are repeated. The third on-period is a period in which the second switching signal S2 among the first switching signal S1 and the second switching signal S2 is at a high level and the first switching signal S1 is at a low level. The fourth period T11 is a charging period of the input inductor Lin. The dead time period Td is a period in which both the first switching signal S1 and the second switching signal S2 are at a low level. The fourth on-period is a period in which the first switching signal S1 among the first switching signal S1 and the second switching signal S2 is at a high level and the second switching signal S2 is at a low level. The fifth period T12 is a discharging period of the input inductor Lin. The sixth period T13 is a zero current period in which no current flows through the input inductor Lin.

[0047] FIGS. 7A, 7B, and 7C are operation explanatory diagrams of the fourth period T11, the fifth period T12, and the sixth period T13 in FIG. 6, respectively. In FIGS. 7A and 7B, the current path of the current i flowing through the input inductor Lin is indicated by a thin broken line. Since the sixth period T13 is a period for making the current flowing through the input inductor Lin zero, the current i flowing through the input inductor Lin is not shown in FIG. 7C. Also, in FIGS. 7A, 7B, and 7C, the current i1 flowing through the inductor L1 is indicated by a thick broken line. L In the fourth period T11 of FIG. 6, since the first semiconductor switching element Q1 is off and the second semiconductor switching element Q2 is on, as shown in FIG. 7A, the current i flows through the input inductor Lin through the path of the second semiconductor switching element Q2 - the second diode D2 - the input inductor Lin. L is not shown. Also, in FIGS. 7A, 7B, and 7C, the current i1 flowing through the inductor L1 is indicated by a thick broken line.

[0048] In the fourth period T11 of FIG. 6, since the first semiconductor switching element Q1 is off and the second semiconductor switching element Q2 is on, as shown in FIG. 7A, the current i flows through the input inductor Lin through the path of the second semiconductor switching element Q2 - the second diode D2 - the input inductor Lin. LA current flows. Also, during the fourth period T11, a current i1 flows through the path of second capacitor C2 - primary winding N1 - inductor L1 - second semiconductor switching element Q2 - second capacitor C2.

[0049] At the end of the fourth period T11 and after the dead time period Td has elapsed, the voltage across the first semiconductor switching element Q1 has dropped to zero volts. As a result, the first semiconductor switching element Q1 is switched to zero volts at the start of the fifth period T12.

[0050] In the fifth period T12 of Figure 6, the first semiconductor switching element Q1 is ON and the second semiconductor switching element Q2 is OFF. Therefore, as shown in Figure 7B, current i flows to the input inductor Lin through the path of first semiconductor switching element Q1 - first capacitor C1 - second capacitor C2 - second diode D2 - input inductor Lin. L A current flows. Also, in the fifth period T12 of Figure 6, a current i1 flows through the path of first capacitor C1 - first semiconductor switching element Q1 - inductor L1 - primary winding N1 - first capacitor C1.

[0051] In the sixth period T13 of Figure 6, as shown in Figure 7C, current i1 flows through the path of first capacitor C1 - first semiconductor switching element Q1 - inductor L1 - primary winding N1 - first capacitor C1.

[0052] The control device 5 controls the current i flowing through the input inductor Lin, for example, as shown in Figure 5. L The first semiconductor switching element Q1 and the second semiconductor switching element Q2 are controlled so that the mode becomes a current discontinuity mode. Figure 5 also shows the waveform of the input current Iin flowing from the AC power supply 8 to the converter device 1.

[0053] In converter device 1, the inductance of the input inductor Lin is set to L in Let i be the current flowing through the input inductor Lin. L The peak value of the wave is i Lmax Then, i Lmax This is expressed by equation (1).

[0054]

number

[0055] Therefore, in the converter device 1, the first period T1 and the inductance L in If each is constant, the current i is proportional to the instantaneous value of the input voltage Vin. L wave peak i Lmax Because this changes, it becomes possible to improve the power factor.

[0056] Furthermore, the control device 5 controls the DC bus voltage Vdc (see Figure 1) of the half-bridge inverter 3 and controls the output voltage Vo (see Figure 1) of the full-bridge inverter 4. The DC bus voltage Vdc is the voltage across the second series circuit 32 of the first capacitor C1 and the second capacitor C2.

[0057] The maximum value (peak value) of the input voltage Vin from the AC power supply 8 to the converter device 1 is V max Let Po be the output power of converter device 1, Tsw be the switching period of half-bridge inverter 3 (see Figures 3 and 5), Ton (=T1) be the on time in the switching period Tsw of half-bridge inverter 3 (the period during which the first switching signal S1 and the second switching signal S2 are both at a high level), and L be the inductance of input inductor Lin. in Therefore, the DC bus voltage Vdc is expressed by equation (2).

[0058]

number

[0059] In the converter device 1, the control device 5 sets the duty cycle of the first switching signal S1 and the second switching signal S2 to 50%, so if the output power Po is constant, it is possible to keep the DC bus voltage Vdc constant.

[0060] Furthermore, the control device 5 controls the output voltage command value Vo of the full-bridge inverter 4. * Based on the detected output voltage Vo of the full-bridge inverter 4, PI control is performed to control the phase difference θ1 (see Figure 2) between the output voltage V1 of the half-bridge inverter 3 and the input voltage V2 of the full-bridge inverter 4. The phase difference θ1 between the output voltage V1 of the half-bridge inverter 3 and the input voltage V2 of the full-bridge inverter 4 is the same as the phase difference θ (see Figure 2) between the first switching signal S1 and the third switching signal S3.

[0061] If the output power of converter device 1 is Po, the number of turns of the primary winding N1 of transformer Tr1 is n1, the number of turns of the secondary winding N2 is n2, the inductance of inductor L1 is L1, and the value obtained by converting the phase difference θ to radians is δ, then the output power Po is expressed by equation (3).

[0062]

number

[0063] As shown in Figure 1, the control device 5 includes a first subtraction unit 51, a first PI control unit 52, and a generation unit 55. The first subtraction unit 51 calculates the output voltage command value Vo * The difference voltage value between the output voltage Vo and the first PI control unit 52 is calculated. The first PI control unit 52 sets a phase difference command value θ for feedback control to bring the difference value obtained by the first subtraction unit 51 closer to zero. * This generates the output voltage command value Vo. * The half-bridge inverter 3 and full-bridge inverter 4 are controlled to reduce the voltage difference between the output voltage Vo and the current signal. More specifically, the generation unit 55 sets the phase difference θ between the first switching signal S1 and the third switching signal S3 to a phase difference command value θ. * The first switching signal S1 and the third switching signal S3 are generated to the value of , the second switching signal S2 is generated based on the first switching signal S1, and the fourth to sixth switching signals S4 to S6 are generated based on the third switching signal S3. Output voltage command value Vo *The output voltage command value Vo is determined in the first control device 5 by a first external command from a second control device, which is separate from the first control device 5, to the first control device 5. In other words, the first control device 5 determines the output voltage command value Vo based on the first external command from the second control device. * It has the function of generating the output voltage command value Vo. * This is pre-programmed and stored in the first control device 5.

[0064] The first external command is, for example, a command relating to the output voltage Vo of the converter device 1. For communication of the first external command from the second control device to the first control device 5, a communication protocol such as MODBUS, CAN, or other serial communication protocols can be used. The second control device may be, for example, an external controller. Using a communication protocol is not mandatory for communication of external commands from the second control device to the first control device 5. Furthermore, the second control device may be another system microcomputer mounted on the same board as the first control device 5.

[0065] By the way, in converter device 1, if the switching period Tsw of the first semiconductor switching element Q1 and the second semiconductor switching element Q2 is kept constant, when the output power Po fluctuates due to fluctuations in the load connected to converter device 1, the DC bus voltage Vdc fluctuates as can be seen from equation (2) above. For example, as shown in Figure 8, when the switching frequency fsw (=1 / Tsw) is 50kHz, when the output power falls below 100W, the DC bus voltage Vdc fluctuates to the DC bus voltage command value Vdc * It will rise even higher.

[0066] Therefore, the control device 5 sets the DC bus voltage command value Vdc of the half-bridge inverter 3. *The switching frequencies fsw of the first semiconductor switching element Q1 and the second semiconductor switching element Q2 are controlled by PI control based on the detected value of the DC bus voltage Vdc of the half-bridge inverter 3. The control device 5 also sets the switching frequencies of the third semiconductor switching element Q3, the fourth semiconductor switching element Q4, the fifth semiconductor switching element Q5, and the sixth semiconductor switching element Q6 to be the same as the switching frequencies fsw of the first semiconductor switching element Q1 and the second semiconductor switching element Q2. In other words, in the converter device 1, the control device 5 controls the DC bus voltage Vdc by controlling the first to sixth semiconductor switching elements Q1 to Q6 using PFM (Pulse Frequency Modulation).

[0067] The control device 5 includes a second subtraction unit 53 and a second PI control unit 54. The second subtraction unit 53 controls the DC bus voltage command value Vdc * The difference voltage value between the DC bus voltage Vdc and the value obtained by the second subtraction unit 53 is calculated. The second PI control unit 54 sets a switching frequency command value fsw for feedback control to bring the difference voltage value obtained by the second subtraction unit 53 closer to zero. * This generates the DC bus voltage command value Vdc. * The control device 5 controls the half-bridge inverter 3 and the full-bridge inverter 4 to reduce the voltage difference between the DC bus voltage Vdc and the DC bus voltage Vdc. More specifically, the control device 5 controls the switching frequency fsw value of the first to sixth switching signals S1 to S6 to the switching frequency command value fsw * Change the value to the DC bus voltage command value Vdc. * This is determined in the first control unit 5 by a second external command from the second control unit to the first control unit 5. In other words, the first control unit 5 determines the DC bus voltage command value Vdc based on the second external command from the second control unit. * It has the function of generating [something].

[0068] The second external command is, for example, a command relating to the DC bus voltage Vdc of the converter device 1. For the communication of the second external command from the second control device to the first control device 5, a communication protocol such as MODBUS, CAN, or other serial communication protocols can be used. The second control device may be, for example, an external controller. Using a communication protocol is not mandatory for the communication of the second external command from the second control device to the first control device 5.

[0069] In converter device 1, control device 5 sets the DC bus voltage command value Vdc * By controlling the switching frequency fsw of the first semiconductor switching element Q1 and the second semiconductor switching element Q2 through PI control based on the detected value of the DC bus voltage Vdc, even if the output power Po of the converter device 1 fluctuates due to load fluctuations, the DC bus voltage Vdc is controlled to the DC bus voltage command value Vdc. * It becomes possible to control the value to approach that value.

[0070] The execution entity of the control device 5 includes a computer system. The computer system has one or more computers. The computer system mainly consists of a processor and memory as hardware. The function of the control device 5 as the execution entity in this disclosure is realized by the processor executing a program recorded in the memory of the computer system. The program may be pre-recorded in the memory of the computer system, or it may be provided via a telecommunications line, or it may be recorded and provided on a non-temporary recording medium such as a memory card, optical disk, or hard disk drive (magnetic disk) that can be read by the computer system. The processor of the computer system consists of one or more electronic circuits including semiconductor integrated circuits (ICs) or large-scale integrated circuits (LSIs). The multiple electronic circuits may be aggregated on a single chip or distributed across multiple chips. The multiple chips may be aggregated on a single device or distributed across multiple devices.

[0071] (3) Examples of characteristics of converter devices Figure 9 shows the input voltage Vin, input current Iin, and current i L The waveforms of the output voltage V1, current i1, input voltage V2, and current i2 are shown. Current i2 is the current flowing through the secondary winding N2 of transformer Tr1. Figure 9 illustrates a case where the output power Po fluctuates from 100W to 50W due to load fluctuations during the operation of converter device 1.

[0072] Figure 10A is an enlarged view of the horizontal axis when the output power Po is 100W, with input voltage Vin and current i L The waveforms of the output voltage V1, current i1, input voltage V2, and current i2 are shown. Figure 10B is an enlarged view of the horizontal axis when the output power Po is 50W, showing the input voltage Vin and current i L The waveforms of the output voltage V1, current i1, input voltage V2, and current i2 are shown.

[0073] Figures 10A and 10B show that the length of one period of the output voltage V1 is different when the output power Po is 100W and when it is 50W, while the peak value of the output voltage V1 is the same. The switching frequency fsw when the output power Po is 100W is, for example, 60kHz, and the switching frequency fsw when the output power Po is 50W is, for example, 100kHz. The length of one period of the output voltage V1 when the output power Po is 100W is 16.4μs, and the length of one period of the output voltage V1 when the output power Po is 50W is 10μs.

[0074] (4) Summary The converter device 1 according to Embodiment 1 comprises a rectifier 2, a half-bridge inverter 3, an input inductor Lin, a transformer Tr1, a full-bridge inverter 4, an inductor L1, and a control device 5. The rectifier 2 is composed of a first diode D1 and a second diode D2 connected in series with the first diode D1. In the rectifier 2, the first AC output terminal 81 of the AC power supply 8 is connected to the connection point 21 between the first diode D1 and the second diode D2. The half-bridge inverter 3 has a first series circuit 31 of a first semiconductor switching element Q1 and a second semiconductor switching element Q2, and a second series circuit 32 of a first capacitor C1 and a second capacitor C2. The second series circuit 32 is connected in parallel with the first series circuit 31. In the half-bridge inverter 3, the first semiconductor switching element Q1 is connected to the cathode of the first diode D1, and the second semiconductor switching element Q2 is connected to the anode of the second diode D2. In the half-bridge inverter 3, the second AC output terminal 82 of the AC power supply 8 is connected to the connection point 33 between the first semiconductor switching element Q1 and the second semiconductor switching element Q2. The input inductor Lin is connected between the AC power supply 8 and the rectifier 2. The transformer Tr1 includes a primary winding N1 and a secondary winding N2. The primary winding N1 of the transformer Tr1 is connected between the first output terminal 34 between the first semiconductor switching element Q1 and the second semiconductor switching element Q2 in the half-bridge inverter 3, and between the second output terminal 35 between the first capacitor C1 and the second capacitor C2 in the half-bridge inverter 3. The full-bridge inverter 4 is connected to the secondary winding N2 of the transformer Tr1. The full-bridge inverter 4 has a third semiconductor switching element Q3, a fourth semiconductor switching element Q4, a fifth semiconductor switching element Q5, and a sixth semiconductor switching element Q6. The inductor L1 is connected between the first output terminal 34 or the second output terminal 35 of the half-bridge inverter 3 and the primary winding N1. The control device 5 controls the half-bridge inverter 3 and the full-bridge inverter 4.

[0075] According to the converter device 1 of the embodiment 1 described above, it is possible to achieve a high power factor and high efficiency.

[0076] Furthermore, in the converter device 1 according to Embodiment 1, the control device 5 controls the current i flowing through the input inductor Lin. L By controlling the first semiconductor switching element Q1 and the second semiconductor switching element Q2 so that the mode becomes a current discontinuity mode, the power factor can be improved.

[0077] Furthermore, in the converter device 1 according to Embodiment 1, the control device 5 controls the output voltage command value Vo * By using PI control based on the detected output voltage Vo, the phase difference θ1 between the output voltage V1 of the half-bridge inverter 3 and the input voltage V2 of the full-bridge inverter 4 is controlled, thereby enabling control of the output voltage Vo.

[0078] Furthermore, in the converter device 1 according to Embodiment 1, the control device 5 controls the DC bus voltage command value Vdc * Based on the detected value of the DC bus voltage Vdc, PI control is performed to control the switching frequency fsw of the first semiconductor switching element Q1 and the second semiconductor switching element Q2, making the switching frequencies of the third to sixth semiconductor switching elements Q3 to Q6 the same as the switching frequency fsw of the first semiconductor switching element Q1 and the second semiconductor switching element Q2. As a result, the converter device 1 according to Embodiment 1 can suppress fluctuations in the DC bus voltage Vdc of the half-bridge inverter 3 during load fluctuations.

[0079] (Embodiment 2) In the following description, the converter device 1a according to Embodiment 2 will be explained with reference to Figure 11. Regarding the converter device 1a according to Embodiment 2, components similar to those in the converter device 1 according to Embodiment 1 (see Figure 1) will be denoted by the same reference numerals, and their descriptions will be omitted as appropriate.

[0080] (1) Composition The converter device 1a according to Embodiment 2 differs from the converter device 1 according to Embodiment 1 in that it includes a first half-bridge inverter 3A with the same configuration as the half-bridge inverter 3 in the converter device 1 according to Embodiment 1, and includes a second half-bridge inverter 7 and control device 5a instead of the full-bridge inverter 4 and control device 5.

[0081] The first half-bridge inverter 3A has the same configuration as the half-bridge inverter 3, and therefore includes a first semiconductor switching element Q1, a second semiconductor switching element Q2, a first capacitor C1, and a second capacitor C2. The control terminals of the first semiconductor switching element Q1 and the second semiconductor switching element Q2 are connected to the control device 5a. The first semiconductor switching element Q1 is turned on and off in response to a first switching signal S1 provided by the control device 5a. The second semiconductor switching element Q2 is turned on and off in response to a second switching signal S2 provided by the control device 5a.

[0082] The second half-bridge inverter 7 is connected to the secondary winding N2 of the transformer Tr1. The second half-bridge inverter 7 includes a third capacitor C3 and a fourth capacitor C4 instead of the fifth semiconductor switching element Q5 and the sixth semiconductor switching element Q6 in the converter device 1 according to Embodiment 1. The second half-bridge inverter 7 has a series circuit 41 of the third semiconductor switching element Q3 and the fourth semiconductor switching element Q4, a series circuit 43 of the third capacitor C3 and the fourth capacitor C4, and an output capacitor Co. The series circuit 41 of the third semiconductor switching element Q3 and the fourth semiconductor switching element Q4 is connected between the first output terminal 13 and the second output terminal 14. The series circuit 43 of the third capacitor C3 and the fourth capacitor C4 is connected between the first output terminal 13 and the second output terminal 14. The output capacitor Co is connected between the first output terminal 13 and the second output terminal 14.

[0083] Furthermore, the second half-bridge inverter 7 has a third diode D3 and a fourth diode D4. The third diode D3 is connected in antiparallel to the third semiconductor switching element Q3. The fourth diode D4 is connected in antiparallel to the fourth semiconductor switching element Q4.

[0084] In the second half-bridge inverter 7, each of the third semiconductor switching element Q3 and the fourth semiconductor switching element Q4 has a control terminal, a first main terminal, and a second main terminal. The control terminals of the third semiconductor switching element Q3 and the control terminals of the fourth semiconductor switching element Q4 are connected to the control device 5a. The third semiconductor switching element Q3 is turned on and off in response to a third switching signal S3 provided by the control device 5a. The fourth semiconductor switching element Q4 is also turned on and off in response to a fourth switching signal S4 provided by the control device 5a.

[0085] The second half-bridge inverter 7 has a first input terminal 44 between the third semiconductor switching element Q3 and the fourth semiconductor switching element Q4, and a second input terminal 47 between the third capacitor C3 and the fourth capacitor C4. In the second half-bridge inverter 7, the secondary winding N2 of the transformer Tr1 is connected between the first input terminal 44 and the second input terminal 47.

[0086] The control device 5a controls the first half-bridge inverter 3A and the second half-bridge inverter 7. The control device 5a controls the first semiconductor switching element Q1 and the second semiconductor switching element Q2 of the first half-bridge inverter 3A. The control device 5a also controls the third semiconductor switching element Q3 and the fourth semiconductor switching element Q4 of the second half-bridge inverter 7. The control device 5a is configured to provide the first to fourth switching signals (control signals) S1 to S4 to each of the first to fourth semiconductor switching elements Q1 to Q4. The first to fourth switching signals S1 to S4 are gate voltages (gate signals) applied between the control terminals of the first to fourth semiconductor switching elements Q1 to Q4 and the second main terminal in order to turn the first to fourth semiconductor switching elements Q1 to Q4 on and off. The first to fourth switching signals S1 to S4 are voltages whose voltage level changes between a voltage level higher than the threshold voltage (gate threshold voltage) of the first to fourth semiconductor switching elements Q1 to Q4 (hereinafter also referred to as high level) and a voltage level lower than the threshold voltage (hereinafter also referred to as low level). The control device 5a is configured to change the frequency of the first to fourth switching signals S1 to S4. The first to fourth switching signals S1 to S4 are the same as the first to fourth switching signals S1 to S4 described in Embodiment 1.

[0087] The control device 5a controls the output voltage V1a of the first half-bridge inverter 3A and the output voltage Voa of the second half-bridge inverter 7.

[0088] Furthermore, the control device 5a, like the control device 5 of Embodiment 1, sets the duty cycle of the first switching signal S1 that controls the first semiconductor switching element Q1 to 50%, and the duty cycle of the second switching signal S2 that controls the second semiconductor switching element Q2 to 50%.

[0089] Furthermore, the control device 5a sets the duty cycle of the third switching signal S3 that controls the third semiconductor switching element Q3 to 50%, and the duty cycle of the fourth switching signal S4 that controls the fourth semiconductor switching element Q4 to 50%.

[0090] Furthermore, the control device 5a is similar to the control device 5 of Embodiment 1 in that it controls the current i flowing through the input inductor Lin. L The first semiconductor switching element Q1 and the second semiconductor switching element Q2 are controlled so that the mode becomes a current discontinuity mode.

[0091] Furthermore, the control device 5a controls the output voltage command value Voa of the second half-bridge inverter 7. * Based on the detected value of the output voltage Voa of the second half-bridge inverter 7, PI control is performed to control the phase difference between the output voltage V1a of the first half-bridge inverter 3A and the input voltage V2a of the second half-bridge inverter 7.

[0092] Furthermore, the control device 5a controls the DC bus voltage command value Vdc of the first half-bridge inverter 3A. * Based on the detected value of the DC bus voltage Vdc of the first half-bridge inverter 3A, PI control is performed to control the switching frequencies of the first semiconductor switching element Q1 and the second semiconductor switching element Q2, so that the switching frequencies of the third semiconductor switching element Q3 and the fourth semiconductor switching element Q4 are the same as the switching frequencies of the first semiconductor switching element Q1 and the second semiconductor switching element Q2.

[0093] As shown in Figure 11, the control device 5a includes a first subtraction unit 51a, a first PI control unit 52a, and a generation unit 55a. The first subtraction unit 51a generates the output voltage command value Voa * The difference voltage value between the output voltage Voa and the first PI control unit 52a is calculated. The first PI control unit 52a sets a phase difference command value θa for feedback control to bring the difference value obtained by the first subtraction unit 51a closer to zero. * This generates the output voltage command value Voa. *The first half-bridge inverter 3A and the second half-bridge inverter 7 are controlled to reduce the difference voltage value between the first switching signal S1 and the output voltage Voa. More specifically, the generation unit 55a sets the phase difference value between the first switching signal S1 and the third switching signal S3 to the phase difference command value θa * A first switching signal S1 and a third switching signal S3 are generated to the value of , a second switching signal S2 is generated based on the first switching signal S1, and a fourth switching signal S4 is generated based on the third switching signal S3. Output voltage command value Voa * The output voltage command value Voa is determined in the first control device 5a by a first external command from a second control device, which is separate from the first control device 5a, to the first control device 5a. In other words, the first control device 5a determines the output voltage command value Voa based on the first external command from the second control device. * It has the function of generating the output voltage command value Voa. * This is pre-programmed and stored in the first control device 5a.

[0094] The control device 5a includes a second subtraction unit 53a and a second PI control unit 54a. The second subtraction unit 53a controls the DC bus voltage command value Vdc * The difference voltage value between the DC bus voltage Vdc and the value obtained by the second subtraction unit 53a is calculated. The second PI control unit 54a uses a switching frequency command value fsw for feedback control to bring the difference voltage value obtained by the second subtraction unit 53a closer to zero. * This generates the DC bus voltage command value Vdc. * The first half-bridge inverter 3A and the second half-bridge inverter 7 are controlled to reduce the voltage difference between the DC bus voltage Vdc and the DC bus voltage Vdc. More specifically, the control device 5a controls the switching frequency values ​​of the first to fourth switching signals S1 to S4 to the switching frequency command value fsw * Change the value to the DC bus voltage command value Vdc. * This is determined in the first control unit 5a by a second external command from the second control unit to the first control unit 5a. In other words, the first control unit 5a determines the DC bus voltage command value Vdc based on the second external command from the second control unit. *It has the function of generating [something].

[0095] The second external command is, for example, a command relating to the DC bus voltage Vdc of the converter device 1a. For the communication of the second external command from the second control device to the first control device 5a, a communication protocol such as MODBUS, CAN, or other serial communication protocols can be used. The second control device may be, for example, an external controller. Using a communication protocol is not mandatory for the communication of the second external command from the second control device to the first control device 5a.

[0096] In the converter device 1a, the control device 5 sets the DC bus voltage command value Vdc * By controlling the switching frequencies of the first semiconductor switching element Q1 and the second semiconductor switching element Q2 based on the detected value of the DC bus voltage Vdc, the DC bus voltage Vdc can be controlled even if the output power Po of the converter device 1a fluctuates due to load fluctuations, etc. * It becomes possible to control the value to approach that value.

[0097] The execution entity of control device 5a, like the execution entity of control device 5, includes a computer system.

[0098] (2) Summary The converter device 1a according to Embodiment 2 comprises a rectifier 2, a first half-bridge inverter 3A, an input inductor Lin, a transformer Tr1, an inductor L1, a second half-bridge inverter 7, and a control device 5a. The rectifier 2 is composed of a first diode D1 and a second diode D2 connected in series with the first diode D1. In the rectifier 2, the first AC output terminal 81 of the AC power supply 8 is connected to the connection point 21 between the first diode D1 and the second diode D2. The first half-bridge inverter 3A has a first series circuit 31 of a first semiconductor switching element Q1 and a second semiconductor switching element Q2, and a second series circuit 32 of a first capacitor C1 and a second capacitor C2. The first series circuit 31 is connected between the cathode of the first diode D1 and the anode of the second diode D2. The second series circuit 32 is connected in parallel with the first series circuit 31. In the first half-bridge inverter 3A, the second AC output terminal 82 of the AC power supply 8 is connected to the connection point 33 between the first semiconductor switching element Q1 and the second semiconductor switching element Q2. The input inductor Lin is connected between the AC power supply 8 and the rectifier 2. The transformer Tr1 includes a primary winding N1 and a secondary winding N2. The primary winding N1 of the transformer Tr1 is connected between the first output terminal 34 between the first semiconductor switching element Q1 and the second semiconductor switching element Q2 in the first half-bridge inverter 3A, and the second output terminal 35 between the first capacitor C1 and the second capacitor C2 in the first half-bridge inverter 3A. The inductor L1 is connected between the first output terminal 34 or the second output terminal 35 of the first half-bridge inverter 3A and the primary winding N1. The second half-bridge inverter 7 is connected to the secondary winding N2 of the transformer Tr1. The second half-bridge inverter 7 includes a third semiconductor switching element Q3, a fourth semiconductor switching element Q4, a third capacitor C3, and a fourth capacitor C4. The control device 5a controls the first half-bridge inverter 3A and the second half-bridge inverter 7.

[0099] According to the converter device 1a of Embodiment 2, it is possible to achieve a higher power factor and higher efficiency.

[0100] Furthermore, in the converter device 1a according to Embodiment 2, the control device 5a controls the current i flowing through the input inductor Lin. L By controlling the first semiconductor switching element Q1 and the second semiconductor switching element Q2 so that the mode becomes a current discontinuity mode, the power factor can be improved.

[0101] Furthermore, in the converter device 1a according to Embodiment 2, the control device 5a controls the output voltage command value Voa * By using PI control based on the detected value of the output voltage Voa, the phase difference between the output voltage V1a of the first half-bridge inverter 3A and the input voltage V2a of the second half-bridge inverter 7 is controlled, thereby enabling control of the output voltage Voa.

[0102] Furthermore, in the converter device 1a according to Embodiment 2, the control device 5a controls the DC bus voltage command value Vdc * Based on the detected value of the DC bus voltage Vdc, PI control is performed to control the switching frequency fsw of the first semiconductor switching element Q1 and the second semiconductor switching element Q2, making the switching frequency of the third semiconductor switching element Q3 and the fourth semiconductor switching element Q4 the same as the switching frequency fsw of the first semiconductor switching element Q1 and the second semiconductor switching element Q2. As a result, the converter device 1a according to Embodiment 2 can suppress fluctuations in the DC bus voltage Vdc of the first half-bridge inverter 3A during load fluctuations.

[0103] (modified version) Embodiments 1 and 2 described above are merely one of many embodiments of this disclosure. Embodiments 1 and 2 can be modified in various ways depending on the design, etc., as long as the objectives of this disclosure are achieved.

[0104] For example, each of the first semiconductor switching element Q1 and the second semiconductor switching element Q2 is not limited to GaN-based GITs, but may be, for example, a Si-based MOSFET, a SiC-based MOSFET, or an IGBT (Insulated Gate Bipolar Transistor).

[0105] Furthermore, the third to sixth semiconductor switching elements Q3 to Q6 are not limited to n-channel MOSFETs, but may also be p-channel MOSFETs. Also, the MOSFETs constituting the third to sixth semiconductor switching elements Q3 to Q6 are not limited to Si-based MOSFETs, but may also be, for example, SiC-based MOSFETs, IGBTs, or GaN-based GITs.

[0106] Furthermore, in the converter device 1 according to Embodiment 1, the inductor L1 is connected between the first output terminal 34 or the second output terminal 35 of the half-bridge inverter 3 and the primary winding N1. However, as shown in Figure 12, the inductor L1 may be connected between the secondary winding N2 of the transformer Tr1 and the full-bridge inverter 4.

[0107] Furthermore, the transformer Tr1 is not limited to a configuration where the number of turns of the primary winding N1 is greater than the number of turns of the secondary winding N2; it may also be a configuration where the number of turns of the secondary winding N2 is greater than the number of turns of the primary winding N1.

[0108] Furthermore, the input filter 6 is not limited to an LC filter; for example, it may be a common-mode filter.

[0109] In the converter device 1, the input inductor Lin is not limited to being connected between the AC power supply 8 and the rectifier 2, but may also be connected between the AC power supply 8 and the half-bridge inverter 3.

[0110] In the converter device 1, the input inductor Lin is not limited to being connected between the AC power supply 8 and the rectifier 2, but may also be connected between the AC power supply 8 and the first half-bridge inverter 3A.

[0111] (Aspect) Based on embodiments 1 and 2 described above, the following embodiments are disclosed in this specification.

[0112] The converter device (1) according to the first embodiment includes a rectifier (2), a half-bridge inverter (3), an input inductor (Lin), a transformer (Tr1), a full-bridge inverter (4), an inductor (L1), and a control device (5). The rectifier (2) is composed of a first diode (D1) and a second diode (D2) connected in series with the first diode (D1). In the rectifier (2), the first AC output terminal (81) of the AC power supply (8) is connected to the connection point (21) between the first diode (D1) and the second diode (D2). The half-bridge inverter (3) has a first series circuit (31) of a first semiconductor switching element (Q1) and a second semiconductor switching element (Q2), and a second series circuit (32) of a first capacitor (C1) and a second capacitor (C2). The second series circuit (32) is connected in parallel with the first series circuit (31). In the half-bridge inverter (3), the first semiconductor switching element (Q1) is connected to the cathode of the first diode (D1), and the second semiconductor switching element (Q2) is connected to the anode of the second diode (D2). In the half-bridge inverter (3), the second AC output terminal (82) of the AC power supply (8) is connected to the connection point (33) between the first semiconductor switching element (Q1) and the second semiconductor switching element (Q2). The input inductor (Lin) is connected between the AC power supply (8) and the rectifier (2) or the half-bridge inverter (3). The transformer (Tr1) includes a primary winding (N1) and a secondary winding (N2). The transformer (Tr1) has a primary winding (N1) connected between the first output terminal (34) between the first semiconductor switching element (Q1) and the second semiconductor switching element (Q2) in the half-bridge inverter (3), and between the second output terminal (35) between the first capacitor (C1) and the second capacitor (C2) in the half-bridge inverter (3). The full-bridge inverter (4) is connected to the secondary winding (N2) of the transformer (Tr1). The full-bridge inverter (4) has a third semiconductor switching element (Q3), a fourth semiconductor switching element (Q4), a fifth semiconductor switching element (Q5), and a sixth semiconductor switching element (Q6).The inductor (L1) is connected between the first output terminal (34) of the half-bridge inverter (3) and the primary winding (N1), or between the second output terminal (35) of the half-bridge inverter (3) and the primary winding (N1), or between the secondary winding (N2) and the full-bridge inverter (4). The control device (5) controls the half-bridge inverter (3) and the full-bridge inverter (4).

[0113] According to the converter device (1) of the first embodiment, it is possible to achieve a higher power factor and higher efficiency.

[0114] In the converter device (1) according to the second embodiment, in the first embodiment, the control device (5) controls the DC bus voltage (Vdc) of the half-bridge inverter (3) and controls the output voltage (Vo) of the full-bridge inverter (4).

[0115] In the converter device (1) according to the third embodiment, in the second embodiment, the control device (5) sets the duty cycle of the first switching signal (S1) that controls the first semiconductor switching element (Q1) to 50%, and the duty cycle of the second switching signal (S2) that controls the second semiconductor switching element (Q2) to 50%.

[0116] In the converter device (1) according to the fourth embodiment, in the second or third embodiment, the control device (5) sets the duty cycle of the third switching signal (S3) that controls the third semiconductor switching element (Q3) to 50%, the duty cycle of the fourth switching signal (S4) that controls the fourth semiconductor switching element (Q4) to 50%, the duty cycle of the fifth switching signal (S5) that controls the fifth semiconductor switching element (Q5) to 50%, and the duty cycle of the sixth switching signal (S6) that controls the sixth semiconductor switching element (Q6) to 50%.

[0117] In the converter device (1) according to the fifth embodiment, in any one of the second to fourth embodiments, the control device (5) controls the current (i) flowing through the input inductor (Lin). LThe first semiconductor switching element (Q1) and the second semiconductor switching element (Q2) are controlled so that the mode of ) becomes a current discontinuity mode.

[0118] The converter device (1) according to the fifth embodiment can improve the power factor.

[0119] In the converter device (1) according to the sixth embodiment, in any one of the second to fifth embodiments, the control device (5) controls the output voltage command value (Vo) of the full-bridge inverter (4). * The phase difference (θ1) between the output voltage (V1) of the half-bridge inverter (3) and the input voltage (V2) of the full-bridge inverter (4) is controlled by PI control based on the detected value of the output voltage (Vo) of the full-bridge inverter (4).

[0120] The converter device (1) according to the sixth embodiment can control the output voltage (Vo) by controlling the phase difference (θ1).

[0121] In the converter device (1) according to the seventh embodiment, in any one of the second to sixth embodiments, the control device (5) controls the DC bus voltage command value (Vdc) of the half-bridge inverter (3). * Based on the detection value of the DC bus voltage (Vdc) of the half-bridge inverter (3), PI control is performed to control the switching frequencies (fsw) of the first semiconductor switching element (Q1) and the second semiconductor switching element (Q2), so that the switching frequencies of the third semiconductor switching element (Q3), the fourth semiconductor switching element (Q4), the fifth semiconductor switching element (Q5), and the sixth semiconductor switching element (Q6) are the same as the switching frequencies (fsw) of the first semiconductor switching element (Q1) and the second semiconductor switching element (Q2).

[0122] According to the converter device (1) of the seventh embodiment, the DC bus voltage (Vdc) can be controlled by controlling the first semiconductor switching element (Q1) and the second semiconductor switching element (Q2) using PFM (Pulse Frequency Modulation), thereby suppressing fluctuations in the DC bus voltage (Vdc) of the half-bridge inverter (3) during load fluctuations.

[0123] The converter device (1a) according to the eighth embodiment includes a rectifier (2), a first half-bridge inverter (3A), an input inductor (Lin), a transformer (Tr1), an inductor (L1), a second half-bridge inverter (7), and a control device (5a). The rectifier (2) is composed of a first diode (D1) and a second diode (D2) connected in series with the first diode (D1). In the rectifier (2), the first AC output terminal (81) of the AC power supply (8) is connected to the connection point (21) between the first diode (D1) and the second diode (D2). The first half-bridge inverter (3A) has a first series circuit (31) of a first semiconductor switching element (Q1) and a second semiconductor switching element (Q2), and a second series circuit (32) of a first capacitor (C1) and a second capacitor (C2). The first series circuit (31) is connected between the cathode of the first diode (D1) and the anode of the second diode (D2). The second series circuit (32) is connected in parallel to the first series circuit (31). In the first half-bridge inverter (3A), the second AC output terminal (82) of the AC power supply (8) is connected to the connection point (33) between the first semiconductor switching element (Q1) and the second semiconductor switching element (Q2). The input inductor (Lin) is connected between the AC power supply (8) and the rectifier (2) or the first half-bridge inverter (3A). The transformer (Tr1) includes a primary winding (N1) and a secondary winding (N2). The transformer (Tr1) has a primary winding (N1) connected between the first output terminal (34) of the first half-bridge inverter (3A) between the first semiconductor switching element (Q1) and the second semiconductor switching element (Q2), and between the first capacitor (C1) and the second capacitor (C2) of the first half-bridge inverter (3A). The inductor (L1) is connected between the first output terminal (34) or the second output terminal (35) of the first half-bridge inverter (3A) and the primary winding (N1). The second half-bridge inverter (7) is connected to the secondary winding (N2) of the transformer (Tr1). The second half-bridge inverter (7) has a third semiconductor switching element (Q3), a fourth semiconductor switching element (Q4), a third capacitor (C3), and a fourth capacitor (C4).The control device (5a) controls the first half-bridge inverter (3A) and the second half-bridge inverter (7).

[0124] According to the converter device (1a) of the eighth aspect, it is possible to achieve a higher power factor and higher efficiency.

[0125] In the converter device (1a) according to the ninth embodiment, as in the eighth embodiment, the control device (5a) controls the DC bus voltage (Vdc) of the first half-bridge inverter (3A) and controls the output voltage (Voa) of the second half-bridge inverter (7).

[0126] In the converter device (1a) according to the tenth embodiment, in the ninth embodiment, the control device (5a) sets the duty cycle of the first switching signal (S1) that controls the first semiconductor switching element (Q1) to 50%, and the duty cycle of the second switching signal (S2) that controls the second semiconductor switching element (Q2) to 50%.

[0127] In the converter device (1a) according to the 11th embodiment, in the 9th or 10th embodiment, the control device (5a) sets the duty cycle of the third switching signal (S3) that controls the third semiconductor switching element (Q3) to 50%, and the duty cycle of the fourth switching signal (S4) that controls the fourth semiconductor switching element (Q4) to 50%.

[0128] In the converter device (1a) according to the 12th embodiment, in any one of the 9th to 11th embodiments, the control device (5a) controls the current (i) flowing through the input inductor (Lin). L The first semiconductor switching element (Q1) and the second semiconductor switching element (Q2) are controlled so that the mode of ) becomes a current discontinuity mode.

[0129] According to the converter device (1a) of the twelfth embodiment, the power factor can be improved.

[0130] In the converter device (1a) according to the 13th embodiment, in any one of the 9th to 12th embodiments, the control device (5a) controls the output voltage command value (Voa) of the second half-bridge inverter (7). * The phase difference between the output voltage (V1a) of the first half-bridge inverter (3A) and the input voltage (V2a) of the second half-bridge inverter (7) is controlled by PI control based on the detected value of the output voltage (Voa) of the second half-bridge inverter (7).

[0131] According to the converter device (1a) of the 13th embodiment, the output voltage (Voa) can be controlled by controlling the phase difference.

[0132] In the converter device (1a) according to the 14th embodiment, in any one of the 9th to 13th embodiments, the control device (5a) controls the DC bus voltage command value (Vdc) of the first half-bridge inverter (3A). * Based on the detection value of the DC bus voltage (Vdc) of the first half-bridge inverter (3A), PI control is performed to control the switching frequencies (fsw) of the first semiconductor switching element (Q1) and the second semiconductor switching element (Q2), making the switching frequencies of the third semiconductor switching element (Q3) and the fourth semiconductor switching element (Q4) the same as the switching frequencies (fsw) of the first semiconductor switching element (Q1) and the second semiconductor switching element (Q2).

[0133] According to the converter device (1a) of the 14th embodiment, the DC bus voltage (Vdc) can be controlled by controlling the first semiconductor switching element (Q1) and the second semiconductor switching element (Q2) using PFM (Pulse Frequency Modulation), thereby suppressing fluctuations in the DC bus voltage (Vdc) of the first half-bridge inverter (3A) during load fluctuations. [Explanation of Symbols]

[0134] 1. 1a Converter device 2 rectifier 3 Half-bridge inverter 3A 1st Half-Bridge Inverter 31 1st series circuit 32 Second series circuit 33 connection points 34 First output terminal 35 Second output terminal 4. Full-bridge inverter 5, 5a Control device 6 Input Filters 7. Second Half-Bridge Inverter 8 AC power supply 81 1st AC output terminal 82 2nd AC output terminal 11. First Input Terminal 12. Second input terminal 13. First output terminal 14. Second output terminal C1 First Capacitor C2 Second Capacitor C3 Third Capacitor C4 Fourth Capacitor Cf Capacitor Co output capacitor D1 First Diode D2 Second Bypass D3 Third Diode D4 4th diode D5 5th Diode D6 6th diode fsw switching frequency fsw * Switching frequency command value L1 Inductor Lf Inductor Lin input inductor Tr1 Transformer N1 Primary winding N2 secondary winding Q1 First semiconductor switching element Q2 Second semiconductor switching element Q3 Third semiconductor switching element Q4 Fourth semiconductor switching element Q5 Fifth semiconductor switching element Q6 Sixth semiconductor switching element S1 First switching signal S2 Second switching signal S3 Third switching signal S4 Fourth switching signal S5 Fifth switching signal S6 6th switching signal V1 Output Voltage V2 Input Voltage Vdc DC bus voltage Vdc * DC bus voltage command value Vin Input Voltage Vo Output Voltage Voa output voltage Vo * Output voltage command value VOA * Output voltage command value θ phase difference θ1 phase difference

Claims

1. A rectifier comprising a first diode and a second diode connected in series with the first diode, wherein the first AC output terminal of the AC power supply is connected to the connection point between the first diode and the second diode, A half-bridge inverter comprising a first series circuit of a first semiconductor switching element and a second semiconductor switching element, and a second series circuit of a first capacitor and a second capacitor connected in parallel to the first series circuit, wherein the first semiconductor switching element is connected to the cathode of the first diode, the second semiconductor switching element is connected to the anode of the second diode, and the second AC output terminal of the AC power supply is connected to the connection point between the first semiconductor switching element and the second semiconductor switching element, An input inductor connected between the AC power supply and the rectifier or the half-bridge inverter, A transformer including a primary winding and a secondary winding, wherein the primary winding is connected between a first output terminal between the first semiconductor switching element and the second semiconductor switching element in the half-bridge inverter, and between a second output terminal between the first capacitor and the second capacitor in the half-bridge inverter, A full-bridge inverter is connected to the secondary winding of the transformer and has a third semiconductor switching element, a fourth semiconductor switching element, a fifth semiconductor switching element, and a sixth semiconductor switching element. An inductor connected between the first output terminal of the half-bridge inverter and the primary winding, or between the second output terminal of the half-bridge inverter and the primary winding, or between the secondary winding and the full-bridge inverter, The system comprises a control device for controlling the half-bridge inverter and the full-bridge inverter, The control device is Control the DC bus voltage of the half-bridge inverter, The output voltage of the aforementioned full-bridge inverter is controlled by Converter device.

2. The control device is The duty cycle of the first switching signal that controls the first semiconductor switching element is set to 50%. The duty cycle of the second switching signal that controls the second semiconductor switching element is set to 50%. The converter device according to claim 1.

3. The control device is The duty cycle of the third switching signal that controls the third semiconductor switching element is set to 50%. The duty cycle of the fourth switching signal that controls the fourth semiconductor switching element is set to 50%. The duty cycle of the fifth switching signal that controls the fifth semiconductor switching element is set to 50%. The duty cycle of the sixth switching signal that controls the sixth semiconductor switching element is set to 50%. The converter device according to claim 1 or 2.

4. The control device controls the first semiconductor switching element and the second semiconductor switching element such that the mode of the current flowing through the input inductor becomes a current discontinuity mode. The converter device according to claim 1 or 2.

5. The control device is The phase difference between the output voltage of the half-bridge inverter and the input voltage of the full-bridge inverter is controlled by PI control based on the output voltage command value of the full-bridge inverter and the detected output voltage value of the full-bridge inverter. The converter device according to claim 1 or 2.

6. The control device is The switching frequencies of the first semiconductor switching element and the second semiconductor switching element are controlled by PI control based on the DC bus voltage command value of the half-bridge inverter and the detected value of the DC bus voltage of the half-bridge inverter. The switching frequencies of the third semiconductor switching element, the fourth semiconductor switching element, the fifth semiconductor switching element, and the sixth semiconductor switching element are made the same as the switching frequencies of the first semiconductor switching element and the second semiconductor switching element. The converter device according to claim 1 or 2.

7. A rectifier comprising a first diode and a second diode connected in series with the first diode, wherein the first AC output terminal of an AC power supply is connected to the connection point between the first diode and the second diode, A first half-bridge inverter comprising a first series circuit of a first semiconductor switching element and a second semiconductor switching element, and a second series circuit of a first capacitor and a second capacitor connected in parallel to the first series circuit, wherein the first semiconductor switching element is connected to the cathode of the first diode, the second semiconductor switching element is connected to the anode of the second diode, and the second AC output terminal of the AC power supply is connected to the connection point between the first semiconductor switching element and the second semiconductor switching element, An input inductor connected between the AC power supply and the rectifier or the first half-bridge inverter, A transformer including a primary winding and a secondary winding, wherein the primary winding is connected between a first output terminal between the first semiconductor switching element and the second semiconductor switching element in the first half-bridge inverter, and between a second output terminal between the first capacitor and the second capacitor in the first half-bridge inverter, An inductor connected between the first output terminal or the second output terminal of the first half-bridge inverter and the primary winding, A second half-bridge inverter is connected to the secondary winding of the transformer and has a third semiconductor switching element, a fourth semiconductor switching element, a third capacitor, and a fourth capacitor. The system comprises a control device for controlling the first half-bridge inverter and the second half-bridge inverter, The control device is Control the DC bus voltage of the first half-bridge inverter, Controlling the output voltage of the second half-bridge inverter, Converter device.

8. The control device is The duty cycle of the first switching signal that controls the first semiconductor switching element is set to 50%. The duty cycle of the second switching signal that controls the second semiconductor switching element is set to 50%. The converter device according to claim 7.

9. The control device is The duty cycle of the third switching signal that controls the third semiconductor switching element is set to 50%. The duty cycle of the fourth switching signal that controls the fourth semiconductor switching element is set to 50%. The converter device according to claim 7 or 8.

10. The control device controls the first semiconductor switching element and the second semiconductor switching element such that the mode of the current flowing through the input inductor becomes a current discontinuity mode. The converter device according to claim 7 or 8.

11. The control device is The phase difference between the output voltage of the first half-bridge inverter and the input voltage of the second half-bridge inverter is controlled by PI control based on the output voltage command value of the second half-bridge inverter and the detected output voltage value of the second half-bridge inverter. The converter device according to claim 7 or 8.

12. The control device is The switching frequencies of the first semiconductor switching element and the second semiconductor switching element are controlled by PI control based on the DC bus voltage command value of the first half-bridge inverter and the detected value of the DC bus voltage of the first half-bridge inverter. The switching frequencies of the third semiconductor switching element and the fourth semiconductor switching element are made the same as the switching frequencies of the first semiconductor switching element and the second semiconductor switching element. The converter device according to claim 7 or 8.

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